When cooking food, be it by steaming in rice cookers, for example, or by cooking in oil in deep-fryers, it is observed that cooking fumes are emitted to various extents depending on the type of cooking and on the cooking fluid used, such emitted fumes having a characteristic odor that is generally disliked by the user, and that it is desirable to prevent or to treat.
One of the first known treatment means naturally consists in cooking the food in a closed atmosphere by implementing a suitably leaktight connection between the bowl and the lid of the appliance.
However, for obvious safety reasons, in particular in pressure cookers or in deep fryers, it is always necessary to provide a leakage outlet for the cooking fumes, and that is why such appliances are equipped with means for treating cooking odors in order to rid the cooking fumes of all or some of the volatile molecules responsible for the cooking odor.
Various devices have been devised, and in particular it is known that activated carbon filters can be used that make it possible to retain all or some of the grease, as is described, for example, in Patent FR-1 568 985 or in Patent EP-150 516.
Unfortunately, in order to be effective, activated carbon filters in the cooking appliance must be changed frequently, which constitutes an additional design constraint for the appliance insofar as it is essential to make provision to design a system for fitting and removing the activated carbon filter. In addition, it is observed that the user frequently forgets to change the activated carbon filter, such an operation being perceived as a chore. The combination of all of those reasons makes the use of activated carbon filters ill-suited for treating cooking odors. In addition, they are not absolutely and universally effective and they also allow the stream of treated fumes discharged from the appliance to be seen.
A system for treating frying odors is also known that consists in condensing the cooking fumes in a condensation system mounted in the appliance. Such a system does not suffer from the drawbacks of having to change all or some of the system as is required for activated carbon filters, but it does require the user to perform a relatively tedious action each time a cooking operation is effected. The condensation system must be kept at a very low temperature, e.g. in a freezer, throughout the periods during which it is not in use, and it must then be fitted to the cooking appliance itself before any cooking operation. In addition, that system must then be emptied after the cooking operation. The requirement to make the system cold again prevents another cooking operation from being performed with the same system for 24 hours. This systematic fitting operation can be perceived by the user as an additional chore. Furthermore, condensation systems are generally large in volume, which constitutes a further design constraint insofar as it is necessary to integrate such a system into a cooking appliance whose size must generally be limited.
Finally it is already known that catalytic converters can be used for the purpose of treating cooking odors in particular when fitted to deep fryers. The use of catalytic converters avoids any specific action being necessary, unlike systems including activated carbon filters or condensation systems, because the catalytic converter is installed permanently in the appliance, and thus forms a permanent odor treatment unit.
Unfortunately, the use of a catalytic converter in a food-cooking appliance, and in particular in a deep fryer, is difficult to implement insofar as the temperatures reached can be high and can be dangerous for the structural integrity of the appliance and for the user. In addition, in order to obtain good treatment of the cooking odors, and in order to make the treated and discharged cooking fumes invisible, it is necessary to reach temperatures that are sufficiently high. At the same time, it is not possible, for safety reasons, to prefer operating a catalytic converter at temperatures that are too low because the efficiency of the catalytic converter is then too low, and it is then observed that residual cooking odors remain.
It can thus be understood that integrating catalytic converters into food-cooking appliances, and in particular into deep fryers, is an operation that is difficult to implement, and that it is desirable to design food-cooking appliances that are provided with catalytic converters but that are nevertheless capable of operating under good conditions.